Vibration

[OKElkHunter]

I'm having a vibration when I put my engine in gear and fist start accelerating, also having a hard time getting on step. Boat is a 24' Bayliner with a 5.0 I/O Alpha 1. Running a 16" pitch prop but didn't have any issues until last weekend when we had a guest aboard and again this weekend with 2 guest. Had to move people around to get weight distributed just right so the boat would get up on step. I'm thinking a 14" pitch prop may fix the acceleration to step issue, but the vibration has me a little worried. Does anyone have any ideas what may be the cause of the vibration?

[.338WM]

You damaged the prop on the last trip without realizing it? Have you inspected the prop?

[sweepint]

have you had boat for awhile and have you had others in the boat when you did not have step issues? Have you turned your prop when on the trailer to check is the shaft is bent?

[potbuilder]

U joints ?? turn your wheel hard over and put it in gear, listen for the growl.

[OKElkHunter]

Thanks for the responses. No damage to the prop; I check it each time in and out. Last two trips out we have had guest aboard and had step issues as well as vibration, 4 trips out before, we were alone and no issues or vibration. As soon as I felt the vibration, I suspected it could be a U joint, haven't done the hard turn test. Can I do that test out of the water with the engine flush attached, or do I have to do it in the water?

[DRIFTER_016]

First thing I thought of was the U-joints too.

[potbuilder]

Thanks for the responses. No damage to the prop; I check it each time in and out. Last two trips out we have had guest aboard and had step issues as well as vibration, 4 trips out before, we were alone and no issues or vibration. As soon as I felt the vibration, I suspected it could be a U joint, haven't done the hard turn test. Can I do that test out of the water with the engine flush attached, or do I have to do it in the water?

in the water at idle.

[T.R. Bauer]

A vibration and lack of power show up together.....Is this thing running on all cylinders? A missfire can and will cause both of these at once. How long has the 5.0 been running on that distributor cap, rotor, plugs, and wires? I'd be checking the basics first....like does it have compression, fuel, and spark. However, I was thinking ujoints too with the vibration.....LOL....

[Daveinthebush]

Mine was idling rough and would not get on step and it turned out to be the distributor had rotated as the hold down bolt was loose.

[potbuilder]

maybe the prop hub is starting to spin/slip ?? If your having problems when you load the boat heavier maybe the hub wants to spin ??

[OKElkHunter]

Great advice from all. Thanks everyone.
I'll be making lots of checks over the next few days to isolate and fix the problem. This is the 2nd season on the distributer, wires and plugs. I should also check the timing too, it is idling a little low and gotten hard to start sometimes. Fuel economy has droppped off too.

BOAT: Break Out Another Thousand

[BrownBear]

Sure sounds like engine trouble to me. For a guest or two to make such a difference in a 24' I/O with no known prop damage, I'd have to guess you've got a serious loss of power. Easy to imagine a 4-banger turned 3-banger vibrating like crazy.

[OKElkHunter]

Not vibrating like crazy, just a mild vibration when you first put it in gear and start accelerating, smooths out as RPM increase. I am able to get up to MAX RPM once on step and I'm able to back down to 3800 and stay on step and maintain 22-23 knots with guest. No miss that I can tell. I'm starting to think its tune-up time and I need to check U-Joints. The 16 pitch prop is a little steep for a heavy load according to the prop guy. I have lots of checks to make, thats for sure, but the engine sounds good and idles smooth, just low.

[.338WM]

A vibration and lack of power show up together.....Is this thing running on all cylinders? A missfire can and will cause both of these at once. How long has the 5.0 been running on that distributor cap, rotor, plugs, and wires? I'd be checking the basics first....like does it have compression, fuel, and spark. However, I was thinking ujoints too with the vibration.....LOL....

Sure sounds like engine trouble to me. For a guest or two to make such a difference in a 24' I/O with no known prop damage, I'd have to guess you've got a serious loss of power. Easy to imagine a 4-banger turned 3-banger vibrating like crazy.

Great advice from all. Thanks everyone.
I'll be making lots of checks over the next few days to isolate and fix the problem. This is the 2nd season on the distributer, wires and plugs. I should also check the timing too, it is idling a little low and gotten hard to start sometimes. Fuel economy has droppped off too.

BOAT: Break Out Another Thousand

Yep, a V8 that loses 1 cylinder will turn into a very out of balance V7 and if there is crossfire igniton happening, all the worse. Is this a Vortec engine, or HEI and carb? About the engine sounding fine and idling smooth, ignition breakdown/misfire is often undetectable at idle (without a scope)and not make itself evident until the engine is under load. Having additional weight as you described on the past two trips could very well have been the tipping point to make the weakness noticeable to you.

[OKElkHunter]

Yep, a V8 that loses 1 cylinder will turn into a very out of balance V7 and if there is crossfire igniton happening, all the worse. Is this a Vortec engine, or HEI and carb? About the engine sounding fine and idling smooth, ignition breakdown/misfire is often undetectable at idle (without a scope)and not make itself evident until the engine is under load. Having additional weight as you described on the past two trips could very well have been the tipping point to make the weakness noticeable to you.

HEI with Carb